Tubular element

ABSTRACT

A tubular element including a wall defining therein an inner cavity, and a plurality of microchannels supported by the wall and extending along a length of the wall.

BACKGROUND OF THE INVENTION

The embodiments of the invention relate generally to a tubular element. More specifically, the embodiments relate to a tubular element for a sealed refrigeration system of a refrigerator.

Recent and continuing environmental objectives and directives require the use of more environmentally friendly materials as refrigerants. For example, refrigerants have been changed from Freon to R-134a, and more recently from R-134a to R-600a (i.e., Isobutane). The compositions of refrigerants R-134a and R-600a are well known in the art and therefore are not discussed here.

Different refrigerants have different operating characteristics and the formulation of the newer refrigerants requires significant cost in their development, deployment and subsequent disposal. Thus, reduction of the amount of refrigerant, whether R-134a or R-600a, is a desired feature. For instance, R-600a refrigerators produced for sale in countries that follow the ISO codes can use approximately 150 grams of R-600a refrigerant. However, according to the Underwriters Laboratory (UL) regulations, the maximum amount for R-600a refrigerant charge is 50 grams for a household refrigerator. Complying with this standard, while maintaining energy efficiency and meeting desired performance requirements, is an important challenge for producing R-600a refrigerators to be sold in countries that follow the UL regulations, such as the United States. While the use of a maximum of 150 grams of R-600a refrigerant generally does not require any significant design changes in the sealed refrigeration system, the use of only 50 grams of R-600a refrigerant requires some design changes in the sealed refrigeration system.

Hence, there is a need in the industry for a tube element for a sealed refrigeration system of a household refrigerator, which allows the use of only 50 grams of R-600a refrigerant in the sealed refrigeration system without substantially reducing the heat exchange area of such system.

BRIEF DESCRIPTION OF THE INVENTION

One aspect of the invention relates to a tubular element including a wall defining therein an inner cavity, and a plurality of microchannels supported by the wall and extending along a length of the wall.

Another aspect of the invention relates to a refrigerator which includes a sealed refrigeration system containing a refrigerant and including a tubular element for receiving the refrigerant. The tubular element includes a wall defining therein an inner cavity, and a plurality of microchannels distributed in the wall and extending along a length of the wall. The refrigerant flows through the microchannels.

These and other aspects and advantages of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. Furthermore, it is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity many other elements found in conventional systems of the type described herein. Those of ordinary skill of the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of an exemplary refrigerator employing an exemplary tube element in accordance with the invention;

FIG. 2 is a perspective view of the refrigerator of FIG. 1 with the doors for the fresh food compartment and the freezer compartment being removed and with the sealed refrigeration system being schematically illustrated;

FIG. 3 is a perspective view of a first exemplary embodiment of a tube element in accordance with the invention;

FIG. 4 is a cross-sectional view of a second exemplary embodiment of the tube element in accordance with the invention; and

FIG. 5 is a cross-sectional view of a third exemplary embodiment of the tube element in accordance with the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION

Referring now to FIGS. 1 and 2, an exemplary refrigerator employing an exemplary embodiment of a tube element in accordance with the invention is generally designated by reference numeral 10. The refrigerator 10 has a main body 11 which defines therein a first, upper, fresh food compartment 12 with a frontal access opening 12A and a second, lower, freezer compartment 14 with a frontal access opening 14A. The fresh food compartment 12 and the freezer compartment 14 are arranged in a bottom mount configuration where the fresh food compartment 12 is disposed or positioned above the freezer compartment 14. A mullion 20 separates the fresh food compartment 12 from the freezer compartment 14.

The fresh food compartment 12 is shown with two French doors 15 and 16, which are rotatably attached to the main body 11 in a known manner. However, a single door can be used instead of the doors 15, 16. The freezer compartment 14 is closed by a drawer or a door 17. When a door is used for the freezer compartment 14, it is rotatably attached to the main body 11 in a known manner. When a drawer is used for the freezer compartment 14, it is slidably received in the interior or cavity defined by the freezer compartment 14 in a known manner. The drawer/door 17 and the doors 15, 16 close the frontal access openings 14A, 12A, respectively.

In FIGS. 1 and 2, the refrigerator 10 is shown as a bottom mount refrigerator, but in alternate embodiments the refrigerator 10 may be any type of refrigerators. Therefore, the present invention is not intended to be limited to any particular type of refrigerator.

As clearly shown in FIG. 2, the refrigerator 10 has a sealed refrigeration system 21, which includes an evaporator 22 disposed in the freezer compartment 14, a compressor 23 disposed downstream of the evaporator 22 and outside of the freezer compartment 14 (usually in the mechanical compartment of the refrigerator 10, not shown), a condenser 24 disposed downstream of the compressor 23 and outside of the freezer compartment 14 and exposed to the air surrounding the refrigerator 10 (i.e., the ambient air), an expansion valve 25 disposed downstream of the condenser 24 and upstream of the evaporator 22, and a fluid connection loop 26 fluidly connecting these elements 22-25 together. As is known in the art, the condenser 24 includes a series of tube elements and a plurality of fins attached to the tube elements. Similarly, the evaporator 22 may include a series of tube elements. The sealed refrigeration system 21 contains a refrigerant such as R-600a. The operating principle of the sealed refrigeration system 21 is well known in the art, and therefore is not discussed here. Cold air, which is cooled by the evaporator 22, is delivered, through a channel (not shown), to the fresh food compartment 12 to maintain the temperature in the fresh food compartment at a selected level.

FIG. 3 is a cross-sectional view of a first exemplary embodiment of a tube or tubular element in accordance with the invention, which can be used as the tube element for the condenser 24 and/or the evaporator 22 of the sealed refrigeration system 21. In this exemplary embodiment, a plurality of microchannels, microtubes or capillaries 110 is preferably uniformly distributed in the wall 120 of the cylindrical tube element 100 along the circumference or perimeter of the wall 120. The microchannels 110 extend along the length of the wall 120. The tube element 100 is made of a thermally conductive material, such as aluminum, cooper and the like, which provides a heat exchange between the refrigerant flowing within the microchannels 110 and air outside of the tube element 100. In one embodiment, the cylindrical tube element 100 has a diameter (the outer diameter) in the range from about 3/16 inches to about ½ inches. The microchannels 110 could have a cross section of any shape, including circular (see FIGS. 3 and 4). When the cross section of the micro channels 110 is circular, the microchannels 110 each have a diameter in the range from about 0.02 inches to about 0.2 inches. The wall 120 has a thickness so that the thinnest area between the surface of each microchannel 110 and the exterior or interior surface of the cylindrical tube element 100 has a thickness from about 0.015 inches to about 0.25 inches, more preferably from about 0.018 inches to about 0.02 inches.

The wall 120 defines an inner cavity 130 which may be maintained unfilled. In another aspect of the invention, the inner cavity 130 of the tube element 100 may be at least partially filled to reduce the volume of the inner cavity.

The use of the microchannels 110 within the wall 120 of the tube element 100 is advantageous as less refrigerant is used while the airside heat transfer area of the tube element remains comparable to conventional tube elements.

FIG. 4 is a cross-sectional view of a second exemplary embodiment 200 of the tube element in accordance with the invention, wherein a protective sleeve such as a sheath 140 is used. In FIG. 4, the sheath 140 is shown as surrounding and in direct contact with the wall 120. The sheath 140 can be spaced apart from the wall 120 so that there is an annular gap between the sheath 140 and the wall 120. In this later configuration, however, a thermally conductive fluid is used to fill up such a gap. This sheath 140 is used to contain the refrigerant in the event of a leak. The sheath 140 allows the cooling system to receive a higher classification with respect to U.L. codes. The sheath 140 is preferably made of a metal, such as aluminum.

FIG. 5 is a cross-sectional view of a third exemplary embodiment 300 of the tube element in accordance with the invention, wherein the wall 120′ of the tube element 300 has a non-circular shaped cross section such as a generally D-shaped cross section. The D-shaped wall 120′ may facilitate the installation of the tube element 300 as the flat surface thereof may be used for attachment to a flat support surface.

It would be recognized by those skilled in the art that the wall of tube element 100, 200, 300 may also be formed in other shapes, such as oval, rectangular, square, to increase the heat exchange surface.

While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims. Moreover, features of various embodiments/variations can be combined. Thus, while there have shown, described and pointed out fundamental novel features of the invention as applied to various specific embodiments thereof, it will be understood that various omissions, substitutions and changes in the form and details of the devices illustrated and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

1. A tubular element comprising: a wall defining therein an inner cavity, and a plurality of microchannels supported by the wall and extending along a length of the wall.
 2. The tubular element of claim 1, wherein the microchannels are embedded in the wall.
 3. The tubular element of claim 2, wherein the microchannels are uniformly distributed along a perimeter of the wall.
 4. The tubular element of claim 3, further comprising a protective sleeve surrounding and in thermal contact with the wall.
 5. The tubular element of claim 3, wherein the wall has a non-circular shaped cross section.
 6. The tubular element of claim 5, wherein the wall has substantially D-shaped cross section.
 7. The tubular element of claim 3, wherein the wall has a substantially circular-shaped cross section.
 8. The tubular element of claim 3, wherein the tubular element comprises a thermally conductive material.
 9. The tubular element of claim 7, wherein the thermally conductive material comprises aluminum.
 10. A refrigerator comprising: a sealed refrigeration system containing a refrigerant and comprising a tubular element for receiving the refrigerant, the tubular element comprising: a wall defining therein an inner cavity, and a plurality of microchannels embedded in the wall and extending along a length of the wall, wherein the refrigerant flows through the microchannels.
 11. The refrigerator of claim 10, wherein the microchannels are uniformly distributed along a perimeter of the wall.
 12. The refrigerator of claim 10, wherein the tubular element further comprises a protective sleeve surrounding and in thermal contact with the wall.
 13. The refrigerator of claim 10, wherein the tubular element is used as at least one of a condenser tube and an evaporator tube of the sealed refrigeration system.
 14. The refrigerator of claim 10, wherein the wall has a non-circular shaped cross section.
 15. The refrigerator of claim 14, wherein the wall has a substantially D-shaped cross section.
 16. The refrigerator of claim 10, wherein the wall has a substantially circular-shaped cross section.
 17. The refrigerator of claim 10, wherein the tubular element comprises aluminum. 